Interferometric optical imaging has emerged as a powerful technology for high resolution (.about..mu.m) visualization of microstructural optical properties such as absorption, scattering, loss, birefringence, and spectroscopic analysis. Several embodiments of this imaging technology require a mechanically scanned reference arm. For instance, in optical coherence domain reflectometry (OCDR) a longitudinally scanned reference arm and a broad bandwidth light source are used to create reflectivity profiles of a sample's optical properties. Due to the broad bandwidth of the optical source, as the reference arm mirror is translated, optical interference between reflections from the reference mirror and reflections or scattering sites within the sample, is detected at the photodetector when the respective path lengths are matched to within the source coherence length. Such mechanical scanning can lead to low image acquisition speed, limiting utility in many applications. Techniques based on optical frequency domain reflectometry (OFDR) ideally have no moving parts and thus potentially can scale to high rate imaging. However, today's known OFDR embodiments typically suffer from poor system dynamic range and sensitivity, limited potential imaging speed, and poor linewidth or resolution.
The present invention seeks to overcome these limitations.